1 #!/usr/bin/env python
2 # -*- coding: utf-8 -*-
3 #
4 # Copyright (C) 2018-2023 Free Software Foundation, Inc.
5 # Contributed by Bernhard Reutner-Fischer <aldot@gcc.gnu.org>
6 # Inspired by bloat-o-meter from busybox.
7
8 # This software may be used and distributed according to the terms and
9 # conditions of the GNU General Public License as published by the Free
10 # Software Foundation.
11
12 # For a set of object-files, determine symbols that are
13 # - public but should be static
14
15 # Examples:
16 # unused_functions.py ./gcc/fortran
17 # unused_functions.py gcc/c gcc/c-family/ gcc/*-c.o | grep -v "'gt_"
18 # unused_functions.py gcc/cp gcc/c-family/ gcc/*-c.o | grep -v "'gt_"
19
20 import sys, os
21 from tempfile import mkdtemp
22 from subprocess import Popen, PIPE
23
24 def usage():
25 sys.stderr.write("usage: %s [-v] [dirs | files] [-- <readelf options>]\n"
26 % sys.argv[0])
27 sys.stderr.write("\t-v\tVerbose output\n");
28 sys.exit(1)
29
30 (odir, sym_args, tmpd, verbose) = (set(), "", None, False)
31
32 for i in range(1, len(sys.argv)):
33 f = sys.argv[i]
34 if f == '--': # sym_args
35 sym_args = ' '.join(sys.argv[i + 1:])
36 break
37 if f == '-v':
38 verbose = True
39 continue
40 if not os.path.exists(f):
41 sys.stderr.write("Error: No such file or directory '%s'\n" % f)
42 usage()
43 else:
44 if f.endswith('.a') and tmpd is None:
45 tmpd = mkdtemp(prefix='unused_fun')
46 odir.add(f)
47
48 def dbg(args):
49 if not verbose: return
50 print(args)
51
52 def get_symbols(file):
53 syms = {}
54 rargs = "readelf -W -s %s %s" % (sym_args, file)
55 p0 = Popen((a for a in rargs.split(' ') if a.strip() != ''), stdout=PIPE)
56 p1 = Popen(["c++filt"], stdin=p0.stdout, stdout=PIPE,
57 universal_newlines=True)
58 lines = p1.communicate()[0]
59 for l in lines.split('\n'):
60 l = l.strip()
61 if not len(l) or not l[0].isdigit(): continue
62 larr = l.split()
63 if len(larr) != 8: continue
64 num, value, size, typ, bind, vis, ndx, name = larr
65 if typ == 'SECTION' or typ == 'FILE': continue
66 # I don't think we have many aliases in gcc, re-instate the addr
67 # lut otherwise.
68 if vis != 'DEFAULT': continue
69 #value = int(value, 16)
70 #size = int(size, 16) if size.startswith('0x') else int(size)
71 defined = ndx != 'UND'
72 globl = bind == 'GLOBAL'
73 # c++ RID_FUNCTION_NAME dance. FORNOW: Handled as local use
74 # Is that correct?
75 if name.endswith('::__FUNCTION__') and typ == 'OBJECT':
76 name = name[0:(len(name) - len('::__FUNCTION__'))]
77 if defined: defined = False
78 if defined and not globl: continue
79 syms.setdefault(name, {})
80 syms[name][['use','def'][defined]] = True
81 syms[name][['local','global'][globl]] = True
82 # Note: we could filter out e.g. debug_* symbols by looking for
83 # value in the debug_macro sections.
84 if p1.returncode != 0:
85 print("Warning: Reading file '%s' exited with %r|%r"
86 % (file, p0.returncode, p1.returncode))
87 p0.kill()
88 return syms
89
90 (oprog, nprog) = ({}, {})
91
92 def walker(paths):
93 def ar_x(archive):
94 dbg("Archive %s" % path)
95 f = os.path.abspath(archive)
96 f = os.path.splitdrive(f)[1]
97 d = tmpd + os.path.sep + f
98 d = os.path.normpath(d)
99 owd = os.getcwd()
100 try:
101 os.makedirs(d)
102 os.chdir(d)
103 p0 = Popen(["ar", "x", "%s" % os.path.join(owd, archive)],
104 stderr=PIPE, universal_newlines=True)
105 p0.communicate()
106 if p0.returncode > 0: d = None # assume thin archive
107 except:
108 dbg("ar x: Error: %s: %s" % (archive, sys.exc_info()[0]))
109 os.chdir(owd)
110 raise
111 os.chdir(owd)
112 if d: dbg("Extracted to %s" % (d))
113 return (archive, d)
114
115 def ar_t(archive):
116 dbg("Thin archive, using existing files:")
117 try:
118 p0 = Popen(["ar", "t", "%s" % archive], stdout=PIPE,
119 universal_newlines=True)
120 ret = p0.communicate()[0]
121 return ret.split('\n')
122 except:
123 dbg("ar t: Error: %s: %s" % (archive, sys.exc_info()[0]))
124 raise
125
126 prog = {}
127 for path in paths:
128 if os.path.isdir(path):
129 for r, dirs, files in os.walk(path):
130 if files: dbg("Files %s" % ", ".join(files))
131 if dirs: dbg("Dirs %s" % ", ".join(dirs))
132 prog.update(walker([os.path.join(r, f) for f in files]))
133 prog.update(walker([os.path.join(r, d) for d in dirs]))
134 else:
135 if path.endswith('.a'):
136 if ar_x(path)[1] is not None: continue # extract worked
137 prog.update(walker(ar_t(path)))
138 if not path.endswith('.o'): continue
139 dbg("Reading symbols from %s" % (path))
140 prog[os.path.normpath(path)] = get_symbols(path)
141 return prog
142
143 def resolve(prog):
144 x = prog.keys()
145 use = set()
146 # for each unique pair of different files
147 for (f, g) in ((f,g) for f in x for g in x if f != g):
148 refs = set()
149 # for each defined symbol
150 for s in (s for s in prog[f] if prog[f][s].get('def') and s in prog[g]):
151 if prog[g][s].get('use'):
152 refs.add(s)
153 for s in refs:
154 # Prune externally referenced symbols as speed optimization only
155 for i in (i for i in x if s in prog[i]): del prog[i][s]
156 use |= refs
157 return use
158
159 try:
160 oprog = walker(odir)
161 if tmpd is not None:
162 oprog.update(walker([tmpd]))
163 oused = resolve(oprog)
164 finally:
165 try:
166 p0 = Popen(["rm", "-r", "-f", "%s" % (tmpd)], stderr=PIPE, stdout=PIPE)
167 p0.communicate()
168 if p0.returncode != 0: raise "rm '%s' didn't work out" % (tmpd)
169 except:
170 from shutil import rmtree
171 rmtree(tmpd, ignore_errors=True)
172
173 for (i,s) in ((i,s) for i in oprog.keys() for s in oprog[i] if oprog[i][s]):
174 if oprog[i][s].get('def') and not oprog[i][s].get('use'):
175 print("%s: Symbol '%s' declared extern but never referenced externally"
176 % (i,s))
177
178